Sulfonamide derivatives which inhibit phosphorylation of myosin regulatory light chain and have an intraocular pressure reducing action and neutrophil migration inhibitory action are known (International Publication WO2007/026664), and it has been elucidated that these sulfonamide derivatives are useful as active ingredients of medicaments for prophylactic and/or therapeutic treatment of glaucoma and the like.
However, (S)-1-(4-chloro-5-isoquinolinesulfonyl)-3-(methylamino)pyrrolidine in free base represented by the following formula (1) is not disclosed in International Publication WO2007/026664 (hereinafter in the specification, this compound in a free base may be referred to as “Compound 1”).

Hydrochloride of Compound 1 mentioned above is disclosed in International Publication WO2007/026664, and this hydrochloride is prepared by treating tert-butoxycarbonylated Compound 1 with excessive hydrochloric acid and removing the tert-butoxycarbonyl group (Example 19-3). However, the aforementioned publication discloses only the preparation method, and no description is given as for number of hydrochloric acid molecules added to the resulting (S)-1-(4-chloro-5-isoquinolinesulfonyl)-3-(methylamino)pyrrolidine hydrochloride, physicochemical properties of the resulting hydrochloride and the like.    Patent document 1: WO2007/026664